1. Field of Invention
The present invention relates generally to endless tracks for off-highway vehicles and, more particularly, to a track configuration that minimizes treadwheel vibration. Specifically, the present invention relates to the relationship between the tread angle and wheel width in an endless track that minimize tread-wheel vibration in the wheels about which the track is disposed.
2. Background of the Invention
An endless track is often fabricated from an elastomeric material reinforced with calendared plies of steel belts or the like. The outside surface of the endless track typically is provided with a plurality of spaced lugs that are designed to grip rough, broken, or soft ground and provide traction to the vehicle employing the track. The inner surface of the track typically has a pair of relatively smooth runners spaced from each other by a centrally-disposed lug section that is engaged by a drive wheel to drive a track about the supporting drive wheel assembly. The supporting drive wheel assembly may also have a plurality of bogey wheels and idlers that ride in the smooth runner sections on either side of the lug section. These wheels help maintain alignment of the track about the supporting drive wheel assembly.
Tracked vehicles are typically designed to be operated on rough surfaces, that produce significant vibrations in the vehicle and a generally rough ride. Although surface-related vibrations are expected on rough surfaces, tread-wheel vibration occurs on both rough surfaces and on relatively smooth surfaces. Tread-wheel vibration is caused by the wheels of the vehicle experiencing alternating stiffnesses while traveling over the endless track. The alternating stiffnesses are created by the spaced, exterior lugs of the track. As described above, the lugs are disposed on the outside surface of the track while the wheels engage a relatively smooth inner surface. When a wheel is directly over a lug the track stiffness is relatively firm but is somewhat less stiff when the wheel is over a space between lugs. The stiffnesses create vibrations in the wheels and thus the vehicle.
Thus, it may be understood that tread-wheel vibration would essentially decrease to zero if the lugs were spaced so close together that the wheels did not experience the changes in stiffness. Such a design would not, however, provide sufficient traction.
Tread-wheel vibration is detrimental to the longevity of the wheel bearings, axles, etc. and increases the frequency of maintenance required on the tracked vehicle. Tread-wheel vibration also decreases the comfort of the vehicle's ride. It is thus desirable to provide a track for a vehicle that minimizes tread-wheel vibration. It is thus desirable to provide a vibration-minimizing tread pattern that also provides traction to the vehicle.